Want to get a quick list of all users who have permissions on your SharePoint sites or areas?  Just download SPUtil....

http://download.microsoft.com/download/3/3/c/33cd60dc-92da-411b-af0c-24923caaa28e/SPUtilSuite_Release2.zip

It contains a powerful tool called SPUserUtil. When you run this tool with the Analyze operation (-o analyze) and specify a value for the -webfile parameter the webs manifest XML file it creates contains a nested representation of the user permissions on the sites or portal areas. This way you can easily review your security settings on your portal...